1. Field of the Invention
The invention relates to a test rig for dynamic test assignments on internal combustion engines having a preferably electrical drive and/or loading device which is coupled to a control device for adapting and controlling setpoint values for a speed and a torque characteristic, and a method for operating a test rig with at least one drive and/or loading unit for dynamic test assignments on internal combustion engines, with which setpoint values for the characteristic of at least two variables of the combustion engine, preferably a speed and a torque, are adjusted by means of a drive and or/or loading unit.
2. The Prior Art
A highly dynamic and modern control device of a dynamic engine test rig allows any specified characteristic of speed and torque to be followed almost perfectly. However, this is only possible when the adjustable power of the machines, i.e. of the internal combustion engine and the power brake, is sufficient. In each case, however, this is limited, which leads to a curtailment of the possible characteristics. As two machines are provided on the test rig, two output variables can be controlled. As a rule, these are a speed and a torque. The speed can be the speed of the power brake or the speed of the internal combustion engine. The torque means either the torque of the internal combustion engine which is output at the crankshaft, or the shaft torque or load torque. If characteristics of these variables which the control can no longer achieve due to the limited adjustable power are now specified, then these characteristics must be changed so that they can once again be realized on the test rig.
When the manipulated variables on the test rig are limited, the feedback control can lead to a “wind up” effect. This effect can be recognized by increased overshoot or even a strong tendency of the closed control loop to oscillate and it leads to a loss of controller performance. For this reason, anti-wind-up structures, which are intended to prevent this “wind up” effect, are introduced. These additions to the controller have been in use for a long time.
The object of the present invention was therefore to provide a test rig and a method for its operation with which the setpoint values determined by a speed and a torque characteristic can be optimally adapted and controlled for the respective test assignment so that they can be reproduced on the test rig in the best possible manner.